1. Field of the Invention
This invention relates to material handling vehicles and, more specifically, to detectors for measuring the utilization of such vehicles.
2. Description of the Prior Art
Material handling vehicles, such as bulldozers, excavators, on-highway trucks, wheel loaders and forklifts, currently make use of an engine hour meter to determine the vehicle's utilization, age, value and maintenance schedules. The engine hour meter measures the number of hours the engine has been running and is used in material handling vehicles in much the same manner as an odometer is used in automobiles. The engine hour meter for material handling vehicles and the odometer for automobiles both provide a frame of reference from which to appraise the vehicle's age, value, utilization and maintenance intervals. The engine hour meter is usually triggered to begin timing by way of the engine oil pressure sensor or the engine's alternator.
Maintenance activities, such as oil changes, filter replacement and machine greasing, are usually scheduled according to the number of hours on the engine hour meter. The age of material handling vehicles as well as their components, such as transmissions, torque converters, final drives, tires, undercarriages and engines, are measured according to the vehicle's engine hours. Knowing the number of hours the engine has been running allows an owner to know which components should be replaced or rebuilt. The engine hour reading also provides the owner with a general idea of what the material handling vehicle is worth on the open market. Those machines with high engine hours are deemed to have less value than those with low engine hours.
Most manufacturers of material handling vehicles provide warranties which are based on a certain number of engine hours or a certain period of time, whichever comes first. It is important for owners of new material handling vehicles to monitor their engine hours closely so as to determine whether or not repairs are covered under warranty. The manufacturer is interested in knowing the engine hour reading should there be an early failure of a component since the engine hour reading will give an indication of the wear on the component at the time of failure.
Material handling vehicles are capital items which are generally expensive to purchase and operate. Equipment costs are monitored closely by equipment owners. When calculating equipment costs, the total cost of the equipment is referenced to the engine hour reading so as to arrive at a unit value of dollars per engine hour. Although knowing the total cost is important, it is meaningless unless it can be compared to a time interval, which in the material handling industry is the engine hour. An equipment's cost per engine hour is an industry standard of measure against which material handling vehicles of the same size, class and product family are compared.
Many earthmoving operations use engine hours to determine an equipment operator's productive use of the equipment. The difference between the scheduled hours of operation (the start and end of a shift) and the engine hours clocked on the equipment during the shift provides management with a number against which to judge how effectively the equipment is being utilized.
As indicated above, the role of engine hours in material handling vehicles is regarded as one of the fundamental standards of measurement by those engaged in material handling applications. A problem with using the engine hour meter is that it is limited to recording whether an engine is on or off. Thus, an engine hour meter measures the utilization of the engine, but does not measure the utilization of the material handling vehicle as a whole. The engine hour meter cannot distinguish between the time when a material handling vehicle is idling and the time when a material handling vehicle is in productive use. For those operations where the material handling vehicle sits and idles for a large portion of the time, the use of the engine hour meter to determine the material handling vehicle's utilization, age, value and maintenance schedules would be misleading and costly. Routine maintenance involving oil changes, greasing and filter changes is done unnecessarily on material handling vehicles which spend most of their time idling. Although the engine oil needs to be changed according to the engine hours, the changing of the oil in the transmission and final drives, the greasing of the various joints and the changing of various filters need not be done as often as the engine oil. However, since the only available measure of equipment usage is the engine hour meter, time and money are wasted on performing unnecessary routine maintenance.
Measuring the wear of components based on engine hours can be misleading if the material handling vehicle spends considerable time at rest with the engine idling. Material handling vehicles which spend most of their time idling would be expected to have longer life on their components versus those having less idle time. Should the owner decide to rebuild or replace his components before an anticipated failure based on engine hours, the owner would be replacing or rebuilding components before it was necessary and thereby increasing costs unnecessarily.
A concern that is often voiced by owners of material handling vehicles, as well as manufacturers of material handling vehicles, is that it is difficult to compare component life for material handling vehicles with identical engine hours. A mining truck may wear its tires out in 3,000 engine hours and another mining truck may wear its tires out in 7,000 engine hours. One of the primary factors affecting this difference is the equipment utilization. The truck that wore out its tires in 3,000 engine hours spent most of its time being utilized in productive work while the truck with 7,000 engine hours spent a large portion of its time resting with the engine idling. The engine hour meter is limited in its ability to estimate the wear of major components on material handling vehicles since it does not measure the use of the vehicle as a whole.
Since engine hours are based on the engine running and not on the use of the material handling vehicle, the hourly costs associated with operating the equipment can fluctuate dramatically based on whether or not the equipment spends large periods of time at rest with the engine idling. It is difficult to create and maintain budgets for material handling vehicles when the equipment cost attributed to an hour of engine use can fluctuate as in the case of the tires used in the above example.
The greater the use that owners of material handling vehicles can obtain from their equipment fleet, the greater will be their production in terms of material moved per hour and the lower will be their overall costs. If the material handling vehicle spends most of its time at rest with the engine idling, then its production is low and its costs are high. The high costs are due to fixed costs (loan payments, insurance payments and operator salaries), variable costs (fuel consumption, routine maintenance and repairs) and opportunity costs (the loss of revenues by not having the equipment fleet producing at its maximum potential). The engine hour meter is not able to indicate whether or not the equipment is being utilized versus sitting at rest with the engine idling.
When a used material handling vehicle is sold, the engine hour reading is one of the principal determinants of the equipment's value. For those operations where the material handling vehicle sat at rest with its engine idling for considerable periods of time, the seller would like the potential purchaser to be aware that although the engine hour reading may be high, the machine was not worked hard and spent most of its time idling. The engine hour meter does not allow the purchaser to distinguish between idle hours and "utilization" hours. Consequently, the seller is forced to sell the used material handling vehicle based on its engine hours which do not necessarily reflect the equipment's actual value.
The only way that a material handling vehicle can typically be put to productive use is through an operator. It is the operator who is ultimately responsible for using the equipment. The engine hour meter cannot monitor the operator's use of the equipment since it only monitors that the engine is running. Many operations use the engine hour meter to monitor their operators. At the end of each shift the operator turns in a sheet showing the hours he worked (start of shift to end of shift) and the hours that the engine was running (engine hours accumulated during shift). If the engine hours are unusually low when compared to the scheduled hours, the operator will be held accountable. The limitation of this method of monitoring operators is that an operator can take a long break and leave his equipment idling. This is especially true on night shifts where there may not be a shift foreman on duty and the unsupervised equipment operators could take extended breaks as long as the engines on their material handling vehicles are running. The engine hour meter cannot monitor the operator's productive interaction with the machine.
Manufacturers of material handling vehicles have made great strides in placing sensors on their products to monitor various aspects of their equipment, such as velocity, engine speed and engine temperature. However, to date, there have been no sensors placed on material handling vehicles to monitor that the operator is in fact utilizing the equipment. There have been several efforts by earthmoving equipment manufacturers and after-market manufacturers to place sensors on mining trucks and wheel loaders to measure and monitor their productivity in terms of payload weights and cycle times where production is defined by the weight or volume of material moved in a unit of time, such as tons per engine hour. Since the aim of these efforts is to monitor and measure production, such systems have remained primarily in the domain of earthmoving trucks and wheel loaders where it is possible to measure the weight of payloads. Other types of material handling vehicles such as excavators, bulldozers, draglines, pavers and forklifts, however, have been ignored since their productive capabilities in terms of weight or volume of material moved per unit of time are not amenable to monitoring by sensors. Concern over the amount and rate of production in terms of weight or volume of material moved per unit of time is limiting because only a small number of material handling vehicle families, primarily trucks and wheel loaders, can be measured in this fashion.
Operator incentive programs are often designed around production. For example, a truck operator may be paid a bonus for each additional truck load of material over twenty truck loads of material during his shift. The limitation to production-oriented incentive programs is that they are dependent on the physical geometry of the job layout, which is rarely consistent. Within a given day, week or month, the haul roads may change such that on one day the truck operator is running on a short haul road and therefore able to achieve "bonus loads", but on the next day the truck operator may be required to run on a long haul road and not be able to achieve "bonus loads". Because production in terms of weight, volume or truck loads of material moved per unit of time can fluctuate each day through no fault of the operator, such production oriented incentive programs are not an accurate reflection of an operator's performance. Additionally, such production incentive programs cannot be used for operators of forklifts, bulldozers or excavators since the productive capabilities of these material handling vehicles are difficult if not impossible to continuously measure. Consequently, incentive programs for equipment operators are a hotly debated subject since there is currently no standard of measure which can be applied to various types of material handling vehicles and which directly measures the equipment operator's productive interaction with the equipment.
When a material handling vehicle is being used for productive purposes, it exhibits some form of motion within a certain time interval. Examples of productive use of material handling vehicles are a mining truck carrying a load of material to a dump site, a bulldozer pushing a load of dirt, a forklift carrying a box in a warehouse and a mining truck waiting for the second load of material from a hydraulic shovel. Because productive activities are defined as occurring within a predetermined time interval, even a mining truck waiting for another load of material from a hydraulic shovel is still in productive use even though it is idling between loads. For example, if the hydraulic shovel places a bucket load of material onto the mining truck every forty seconds, then every forty seconds the mining truck will experience a "jolt" when the hydraulic shovel dumps the material from its bucket into the bed of the mining truck. In this example, the previously mentioned time interval would be forty seconds. If the truck experiences no motion for a period longer than forty seconds, however, then it is not being used productively for the total "motionless" period minus forty seconds. All productive activities are characterized by motion occurring within a certain time interval. Consequently, measuring the time that a material handling vehicle is in motion is a measurement of the time that a material handling vehicle is in a state of production. Making a distinction between production (weight or volume of material moved per unit of time) and the state of being in production (utilization of the material handling vehicle) adds an entirely new dimension to the measurement of the productive activities of a material handling vehicle and provides a base against which all material handling vehicles can be measured and compared.
The engine hour meter measures the time an engine is running. An hour of engine use is a combination of the time the equipment is at rest with the engine idling and the time the equipment is in productive use. Consequently, engine hours equal idling hours plus production hours. If the engine hours and the idling hours are known, the production hours can be calculated by subtracting the idling hours from the engine hours. Likewise, if the engine hours and the production hours are known, the idling hours can be calculated by subtracting the production hours from the engine hours. The key is to distinguish between when a material handling vehicle is at rest with the engine idling and when a material handling vehicle is in a state of production. The hours that a material handling vehicle spends in production and the hours that a material handling vehicle spends at rest with the engine idling comprise what is referred to herein as equipment utilization. Production hours are a measure of the material handling vehicle's productive utilization. Idling hours are a measure of the material handling vehicle's non-productive utilization where the material handling vehicle is being utilized but in a non-productive way.
It is, therefore, an object of the present invention to monitor the state of motion of material handling vehicles and to accumulate the time spent in a state of motion on a time accumulator, such as an hour meter and to accumulate the time spent at rest with the engine idling on another time accumulator, such as an hour meter.
It is an object of the present invention to make use of a motion detection apparatus that can distinguish between actual vehicle productive utilization and vehicle vibration caused by engine vibration. The motion detection system is designed in such a way that when attached to a material handling vehicle, the motion detection system can sense motion independently of any of the vehicle's moving parts or fluids, such as transmission, engine, final drives, tires, oil flow or fuel flow.
It is another object of the present invention to provide a utilization detector that is portable, self-contained and isolated from harsh material handling environments and that can easily be placed on any vehicle, new or old.
It is a further object of the present invention to provide a utilization detector that is usable on all material handling vehicles regardless of the family, class or model of vehicle.
Still further objects and advantages will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiment.